Have managed to really have a good go at the 70-200 f/2.8 at the weekend at the British Superbikes. I was there at the same track last year using my 70-300 f/4.5-5.6 and after looking at the most recent pics the 70-200 f/2.8 is worth every penny with regards to image quality. I have also come along a little with my understanding of what the camera/lens does which I suppose helps. But the 70-200 itself has been a big factor in the great images I got.
Dan, if its any help, I had VR turned off taking these shots.